Composite lithium-conductive LATP+PVdF membranes: Development, optimization, and applicability for Li-TEMPO hybrid redox flow batteries

The redox flow batteries (RFBs) are energy storage devices enabling to rationalize energy distribution from renewable sources. The lithium metal hybrid flow batteries (Li-HFBs) represent a very promising type of RFBs distinguished by improved energy and power density, along with the simplified set-up. Unfortunately, the absence of a highly conductive and stable membrane obstructs the intense Li-HFBs evolution. Current research describes the development of Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 -poly(vinylidene fluoride) composite membrane and shows its applicability for Li-HFBs for the first time. The easily fabricated membranes demonstrate high ionic conductivity of 3.4 ∙ 10 −4 S cm −1 (in contrast with 0.74 and 0.16 ∙ 10 −4 S cm −1 of commercially available Nafion and Neosepta, correspondingly) and improved stability towards metallic lithium. The hybrid Li-TEMPO cell with composite membrane shows stable coulombic and energy efficiency (over 95 and 73%, respectively), moderate capacity decay from 2.5 to 1.4 Ah L −1 (preliminarily associated with membrane's permeability), and no membrane degradation after 100 charge/discharge cycles. The combination of functional features established for the proposed composite membranes makes them promising for Li-HFBs, as well as for other energy storage devices, and can potentially accelerate their introduction to the energy storage market. • Integrable ceramic-polymer membranes for lithium hybrid flow batteries were fabricated via the simple tape-casting method. • EIS revealed high ionic conductivity (> 3.4 ∙ 10 -4 S cm -1 ) and high selectivity towards Li + ions of the composite membranes. • Composites showed excellent phase and interfacial stability towards lithium metal unlike to commercially available samples. • Promising cell characteristics and low cost revealed the composite membrane to be prospective for hybrid flow batteries.